Hammer drill



E. A. MORI HAMMER DRILL June 25, 1963 QA/5714. 410i/ 315.1 2215.2 BY 5; ML

E. A. MORI HAMMER DRILL June 25, 1963 2 sheets-sheet 2 Filed Sept. l5, 1961 INVEN TOR. EPA/57' A. M049/ United States Patent i Of 3,095,646 Patented June 25, 1963 ice 3,095,046 HAMMER DREL Ernest A. Mori, Hampton Township, Allegheny County,

Pa., assigner to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Filed Sept. 15, 1961, Ser. No. 138,309 2 Claims. (Si. 173-136) 'Ihis invention relates to rotary percussion drills and in particular concerns a rotary deep well drill having a duid-actuated percussion mechanism of improved construction.

In the drilling of vdeep wells it is recognized that the Vaddi-tion of a percussive action at the drill bit increases the penetration rate of a rotary drill, particularly when drilling in hard formations, such as chert or limestone. It is also known that substantially the Isame or greater penetration rates can be attained with a rotary drill that includes percussive action but with reduced weight on the `drill bit, and experience has shown this to result in a straighter hole. The latter characteristic is particularly important when drilling in steeply `dipping hard formations which tend to deect the drill down dip unless the weight on the bit is kept to a minimum. On the other hand, percussion drill mechanisms necessarily have moving parts that tend to wear and this wear is aggravated if ythe drilling iiuid contains sand or grit as is often the case when drilling hard formations. Furthermore when the drilling iluid is laden with grit it tends to cut out ports. ln prior-art devices the valve ports that successively open and close in the course of the opera-ting cycle of the percussive mechanism are particularly susceptible to such sand cutting with fthe result that the valve soon fails to seat properly and the tool becomes inoperative. .It is the purpose of this invention to provide a rotary percussion mechanism that is particularly adaptable to use with drilling fluid laden with abrasive particles and that continues to operate even though substantial sand cutting has 'taken place. Experience has shown that in the drill of this invention the valve face and valve seat may cut away to a substantial extent and the valve nevertheless continues to function properly, and yonly when the valve face or the valve seat are substantially completely dissipated does the tool cease to function properly. The structure of this invention therefore extends the useful life of the mechanism before it needs to be pulled from the well and repaired or replaced.

'Ihis invention is illustrated in the accompanying drawings that form a part of this specification, and in which,

FIGURE 1 is ya longitudinal section -taken through the upper portion of a preferred embodiment of the drill of this invention;

FIGURE 2 is a longitudinal section taken through the intermediate portion of the drill;

' FIGURE 3 is a longitudinal section taken 'through the lower portion of the drill; and

FIGURES 4 to 8 are diagrammatical representations illustrating successive phases in the cyclic operation of the drill of this invention.

Reference is made to the drawingsin which like numerals indicate fthe same element in the various views and diagrams.

Referring to FIGURES 1, 2, and 3, adapter serves to connect the drill assembly of this invention to the conventional drill stem (not shown) by means of conventional drill-collar threads 11. The drill stem has a central passageway as is conventional for supplying drill-ing iiuid to fthe drill bit and adapter 10 is also provided with a central passage 12 for the purpose of admitting the pressurized drilling duid from the drill `stem to the drill mechanism. A cylindrical upper housing 13 is fastened by threads 14 to adapter 10. A portion 15 of the adapter is of reduced diameter and extends into the upper housing 13 with an annular clearance 16. The annular clearance 16 1s sufhciently large to permit free flow of drilling uid between the portion 15 of the adapter and the inside of upper housing 13, the area of the clearance 16 being preferably substantially the same as that of passage 12. Diagonal openings 17 permit pressurized drilling iluid to pass from passage 12 into annular clearance 16.

'Ihe lower end 7 of the adapter is further reduced in diameter and an open ended cylinder 18 is pressed and shrunk thereon. The Ioutside diameter of cylinder 18 is substantially the same as that of portion 15 ofthe adapter so as to continue the annular lspace 16 substantially unchanged. The cylinder 18 thus forms an inverted cuplike downward extension of adapter 10 and the annular clearance 16 permits the pressurized drilling fluid access to below the cylinder 18.

'Ihe cylindrical upper housing 13 is screwed to an intermediate housing portion 20 (FIGURE 2) to which there is screwed a lower housing 21 whose lower end (FIGURE 3) is internally threaded -to be screwed to bitstem retainer 22 as shown. 'Ihe form and function of the intermediate housing portion 20 will be described later. The lower housing 21 is substantially cylindrical but has a downward-taci g shoulder 23 whose function will become evident. Elements 10, 13, 20, 21, and 22 all have substantially the same outside diameter.

The bit-stem retainer 22 has a central cylindrical bore 24 that is enlarged to have a hexagonal cross section at 25, the lupper part of the hexagonal portion being relieved slightly as shown at 26. The -bit stem 27 has a central passageway 28 and the lower end is provided with female threads 29 that are conventional for attaching any desired type of drill bit (not shown). 'I'he bit stem 27 iS provided with a hexagonal section that is a sliding lit in the hexagonal portion 25 of the bit-stem retainer. 'I'he hexagonal arrangement 25 serves to transmit torque from the tool to the bit through the bit stem 27. Immediately above the hexagonal portion 25 the bit stem has a cylindrical portion 30 that is a sliding tit in the cylindrical bore 24 of the bit-stem retainer. Above this the bit stem has a region of reduced diameter 31, and above this the diameter is again enlarged vat 32 to a diameter that is no larger than that of cylindrical portion 30. Before the bit-stem retainer 22 is screwed onto the lower end of lower housing 21, the bit `stem is inserted in the retainer and the two halves of a split ring 33 are placed around the region 31 of the bit stem, the inside diameter of the split ring 33 being a sliding iit on 31 and the outside diameter of the split ring being such as to slide into the lower end of lower housing 21.

Above the split ring 33 there is located in the housing 21 a guide cage 34 whose top and bottom rings are marked 34t and 34b respectively in FIGURE 3, and between which there are connecting longitudinal legs separated by longitudinal slots. The outside diameter of the legs and rings of guide cage 34 is `such as to t into the lower end of lower housing 21, and its inside diameter is somewhat larger than the diameter of portion 32 of the bit stem. Above the guide cage 34 is a stili spiral clamping spring 36 whose upper end bears against the previously mentioned shoulder 23 of the lower housing 21. The axial dimensions of elements 33, 34, and 36 are made such that when these parts are assembled as shown and the bit-stem retainer 22 is tightened in the lower housing, the clamping spring 36 will be compressed so as to hold the split ring 33 tightly against the upper end of the bitstem retainer. l It will be evident that the bit stem 27 will be allowed a limited amount of longitudinal motion to the extent that the axial length of portion 31 of the bit stem exceeds the axial length of split ring .33. .The axial length of the hexagonal region 25 of the bit stem is slightly less than the mating portion of the bit-stem retainer in order that when weight is applied to the bit, the force is transmitted through the shoulder 37 rather thanthrough the split` ring 33 or the shoulder at the top of the hexagonal .joint 25. The axial length of each of portions 24 and 25 vof the bit stem is of course greater than the longitudinal freedom of the bit stem in its retainer. The upper end 38 of the bit stem forms an anvil upon which the hammer pounds and it may be appropriately heat treated for such service. A plurality of transverse holes 39 and 40 are drilled in the bit stem just below its head for the purpose of permit'- ting free ow of iluid from outside the bit stem to its central passage 28, the holes being staggered so as to minimize any detrimental eiect of the holes on the strength of the bit stem. Above the bit stem there is located an elongate annular hammer Y42 having a central passageway 43. 'Ihe lower end of hammer 42 strikes the anvil surface 38 upon impact and may be appropriately heat treated to withstand such service. A-short way above the lower end of the hammer the outside surface of the hammer is provided with a cylindrical enlargement 44 whose outside diameter is a sliding tit in the guide cage 34. The `construction serves to guide the lower end of the hammer and at the same time iluid may bypass the enlargement 44 through the slots of t-he guide cage B4. It should be noted however, that when the hammer is raised to a point where the enlargement 44 engages the top ring 341? Aof the cage 34 such huid bypass is cut off', and the purpose of this will `be explained later. The top ring 34t forms an :annular ledge .on the inside surface of the housing, and as will become evident later this ledge coacts with the enlargement 44 to provide a hydraulic stop at the top of the upward stroke of the hammer. The body of hammer 42 extending upward and above the enlargement 44 has an outside diameter that is smaller than the inside diameter of lower housing 21 so as to allow an annular space 46 between the hammer and the housing to permit llow of uid longitudinally past the outside of the hammer. At the upwardly facing shoulder 51 (FIGURE 2) the hammer is reduced in diameter to form hammer stem 60 whose upper portion (FIGURE l) is threaded at 62.

Above'the shoulder 23 .the lower housing 21 extends upward with substantially uniform inside diameter but isenlarged somewhat in its upper portion to provide some additional interior vspace kfor a helical compression spring 48. The lower end of spring 48 abuts la collar 49 that is pressed onto the hammer against the shoulder 51. The upper surface of the collar y49 has a `plurality of radial A wear cage 58 is shrunk on the hammer stem 60, being pressed -against a slight upwardly facing shoulder 61. The wear cage 58 comprises top and bottom rings identied in FIGURE 2. by the numerals -58t and SSb respectively, the rings 58t and 58b being connected by a plurality of legs separated by longitudinal slots. The outside diameter of the legs and rings of wear cage 58 forms a sliding -t in the upper portion of wear sleeve 5S. Fl`l1us whenever either of the parts y55 or `58 become excessively worn the part may easily be replaced. The inside diameter of the wear sleeve skirt 54 is larger in diameter than the outside diameter of wear cage -58 in order to permit ilow of iluid between them even though lthe bottom wear cage ring 58b be opposite the skirt 54. The holes 57 thus form communication between the annular spaces on the two sides of the'skirt 54.

The upper end of hammer stem .60 is threaded (FIG- URE l) at 62 and screwed to a piston carrier 63. The piston carrier 63 is somewhat larger in diameter than slots '52 milled therein and the spring A48 rests on the intervening lands. This construction permits free ow of liluid from inside the'spring 48 -to the annular space 46 around the hammer even lthough the spring 48 be tightly compressed as may occur at some phase of the operating cycle. The collar 49 may be somewhat larger in outside diameter than the hammer in order to provide a better supporting surface Ifor the lower end of spring 48, but the outside diameter of collar 49 is less than the -inside diameter of lower housing 21 to permit kiluid ow past the collar. Y

' The upper end of spring 48 abuts the skirt 54 of a wear sleeve 55 shaped substantially as shown in FIGURE Zand whose upper end is pressed and shrunk into the intermediate housing 20 against a downwardly facing shoulder 56 as shown. The upper portion of wear sleeve 5S forms an annular ledge on the inside surface of the housing, and as will become evident this ledge coacts with a ledge `58b on the hammer stern to shut oi the annular space 76 when the hammer approaches its upward limit of travel. The outside diameter of the skirt 54 of the wear sleeve is less than the internaldiameter of lower casing 21, and the skirt is perforated by a plurality of holes 57 whose purpose is to permit iluid tohave access to both sides of spring the diameter of hammer stem 60 so as .to form a downwardly facing shoulder 78. 'Ihe upper end of piston carrier 463 is enlarged to form a piston 72 that is a slid ing lit in cylinder 18. The piston 72 and piston carrier 63 are provided with a central passageway 64.

The internal diameter of intermediate housing portion 20 is larger than the outside diameter of the wear cage 58 to provide an annular clearance between them. At .the upper end of housing'portion 20 (see FIGURE l) the internal bore is enlarged at 65 and a replaceable valve seat 66 is pressed and shrunk into it as shown. The valve seat 66 forms an annular ledge on the inside surface of the housing and its upper portion serves :to coact "the lower end of an annular Valve member 68 to form an annular seal at 67. The internal diameter of the valve seat 66 is larger than the outside diameter of wear cage 58 in order to provide annular clearance between the inside of valveV seat 66 and the top ring 58t Aof the wear cage 5,8. Thus when the hammer is raised the top ring y58t of the wear sleeve may enter the valve seat 66 with vclearance between these elements. The valveY snrface 67 at the upper end of valve seat 66 is frusto-.conical in shape with the apex of the cone pointing downward. The valve seat 66 is easily replaced in the housing por.- tion 20 when it becomes worn or damaged.

An annular valve vmember 68 is ,a Sliding t on the upper end of hammer stem 60. 'Ilhe upper end of the valve member l68 is bored out larger and makes ,a sliding fit on the lower portion of the piston carrier 6 3. The end of skirt -69 of valve element 68 has a truste-conical shape that mates with the valve seat 66 -at the valve surface v67. The internal diameter of the Valve skirt 69 is larger than the outside of weai c age 58. A plurality vof longitudinal slots 70 are milled in the hammer stem- 60 in order Yto provide uid communication between the atlnular space 75 around the hammer stem and ,its central passageway 4 3. Also a plurality of holes 71 are drilled in the hammer stem 60 directly below the shoulder 78 formed by the lower end of the piston carrier for the purpose of preventing uid from being trapped between the valve element and the hammer stem.

The internal diameter of the cylinder 18 must be larger than the diameter of the piston stem 63 in order thatwhen the mechanism is in the conguration illustrated in FIG- URES l, 2, and 3 a lifting force will be exerted on the piston 72 by uid pressure in the annular space 16 inside housing I13 thereby to raise the hammer against the compression of spring 4,8. T-he outside diameter of the valve and valve seat is made larger than the inside diameter of the hammer stem and this gives rise to a downward hydraulic force on valve y68 causing it to remain seated on the valve surface 67 as the hammer starts to lift.

VAt the beginning of .the operating cycle, the hammer will lift until the bottom ring 58b of wear sleeve .58, which forms a collar on the hammer .stemV .60,-r enters upper por-V tion of wear sleeve 55 and this tr'aps iluid in the annular spaces 75 and 76 because the slots 70 will have moved above the valve and will no longer communicate with the annular space 75 and 76. Accordingly, the upward force on the hammer is transferred to the trapped uid in the annular space 75 and 76 and this hydraulic pressure lifts the valve 68 off its seat at the valve surface 67. The longitudinal dimensions of the parts are such that near the top of the hammer stroke the bottom ring 5 8b of the wear cage 58 enters .the upper portion of Iwear sleeve 55, thereby to kick the valve #off its seat hydraulically. When the valve is thus hydraulically opened, the pressurized iluid is momentarily shut `olf `and exerts a lifting force on the valve 68 causing it to move upward to full opening. The upper surface of ring 58h 'is made substantially ilat and horizontal in order that the hydraulic valve kick-olf be sudden so as to quickly lift the valve. As soon as the seal at valve surface 67 is broken, the pressure lifting the hammer is relieved and the hammer decelerates, subsequently falling under the combined action of gravity and of spring 48. Near the end of the upward stroke of the hammer the shoulder 78 of the hammer catches the valve 68 and the valve is forcibly carried down with the hammer. The longitudinal dimensions of the respective various parts are such that with the tool resting on the bit stern shoulder 37 as shown in FIGURES l to 3, the bottom of the hammer will impact the anvil surface 38 (FIGURE 3) before the valve seats at 67. Valve clearance 80 is provided for this purpose, and this linsures that the hammer blow will not be absorbed by the valve. During operation of the tool -with abrasive fluids, the valve clearance 80 gradually increases as the valve and its seat are worn away, but this does not hinder operation of the tool. The hammer stops suddenly upon impact on the anvil surface 38, but the downward momentum of the valve serves to carry the valve downward the extent of the valve clearance to strike its seat and close at 4the valve surface 67. The cycle then repeats itself so long as the tool rests on the bit-stem shoulder 37 and pressurized uid is supplied through the drill pipe.

An important advantage of the invention resides in the vfact that at the top of its stroke the upward motion of the hammer is hydraulically arrested. This feature of vthe invention materially increases the frequency of impact. The hydraulic stop for upward motion :of the hammer is effected when the hammer enlargement 44 (FIGURE 3) enters the top ring 34t of the guide cage 34. The longitudinal dimensions of the respective parts are -such that the enlargement 44 enters the ring 34t a short time after the bottom ring 58h of the wear cage 58 has entered the -wear sleeve 55. Thus when the latter of 4these seals occurs, uid is trapped in the annular space around Ithe hammer and its stem -above the enlargement 44 and Ibelow the ring 58b. Due to the fact that the outside diameter of enlargement 44 is larger than that of ring 58h any further upward movement of the hammer is arrested by compression of fluid trapped in this annular space. The result lis that the upward motion of the hammer assembly is very effectively stopped by hydraulic action, and the hammer quickly reverses and descends. The quick hydraulic reversal of hammer motion at the top of its stroke prevents a dwell at this point and thus increases the cyclic frequency of the percussive action of the drill.

FIGURES 4 to 8 inclusive are diagrammatical illustra- [tions of various phases in the cyclic operation of the tool. FIGURE 4 shows the configuration of the various elements Vat the begining of the operating cycle, the hammer 42 and valve 68 being in their lowermost positions. The valve is closed `and the pressurized uid from the drill pipe exerts a lift on piston 72 which lifts the hammer against compression of spring 48. When the hammer has reached the conguration shown in FIGURE 5, the ring 58h enters the sleeve 55 Iwhereupon fluid is trapped in the annular space 75. Upward momentum of the hammer against the trapped fluid kicks the valve 68 oi its seat 66. As soon as the valve opens, the pressurized uid acting on the lower surface of the valve exerts a lifting nforce on the valve `and .the valve quickly reaches its full-open position as shown in FIGURE 6; Upward motion `of the hammer is subsequently arrested hydraulically as previously explained (but not shown in FIG- URES 4 to v8) and the hammer starts to descend. FIG- URE 7 shows the hammer 42 falling under the action of gravity and spring 48, land -carrying the valve 68 with it. At the bottom of its stroke the hammer strikes the bit stem 27 imparting -a percussive blow. The valve continues downward and closes on its seat, so that at the end of the stroke as shown -in FIGURE 8 Ithe mechanism is again in condition to repeat the cycle.

Provision for bypassing Ithe percussion action for purposes of maintaining uid circulation while running in and out of the hole is not shown in the figures, since such may be conventional, as for example a pressure controlled bypass in a drill-string sub above the percussion mechanism or a conventional shut olf controlled by a ball dropped through lthe `dr-ill pipe from the surface.

.Operational tests made on the drill of this invention under conditions of sand-laden fluid have shown that the valve skirt 69 and the valve seat extension 66 (FIG- URE 1) are both .abraded at the valve surface 67 but the valve surface remains smooth and a tight seal is maintained even though considerable wear of the mating parts takes place. It is believed that due to the rotation of the drill a certain degree of relative rotation of the parts and the iluid stream takes place and this is sucient to eifect uniform circumferential wear observed to take place at the valve surface 67. It has further been found that considerable wear of both the valve seat 66 and the valve skirt 69 may take place without materially affecting the operating eciency of this drill.

What I claim as my invention is:

l. A duid-operated well-drilling mechanism comprising a tubular housing, `an inverted cup-like cylinder longitudinally mounted in the top of said housing, means affording operating iluid access to the interior of said housing Ibelow said cylinder, an elongate annular -hammer smaller in diameter than the inside diameter of said housing and slidablly disposed in and sealed against the inside of ysaid cylinder, said hammer having a longitudinal central passage therethrough, an annular valve slidably disposed on and sealed against the outside surface of said hammer, the inside diameter Vof said valve being Kless than the inside diameter of said cylinder, a passageway leading from said longitudinal central passage of said hammer to a point outside said hammer proximately below said valve, a first annular ledge on the inside surface of said housing below said valve, the lower end of said valve being adapted to seat on the upper portion of said iirst ledge to form an annular seal, a stop on said hammer limiting upward movement of said valve on said hammer, a second annular ledge in said housing below said valve, a collar on said hammer below said second ledge adapted to penetrate said second ledge and form a sliding seal therewith, and a bit stem slidably disposed in Iand sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said Abit stem being disposed to be struck by the lower end of said hammer.

2. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted .cup-like cylinder longitudinally mounted in the top of said housing, means aflfording operating uid Iaccess to the interior of said housing below said cylinder, an elongate annular hammer smaller in diameter than the inside diameter of said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, an annular valve slidably disposed on and sealed against the outside surface of said hammer, the inside diameter of said valve being less than the inside diameter of said cylinder, a rst annular ledge on the inside surface of said housing below said valve, the lower end of said valve being adapted to seat Von the upper portion vof said first ledge to fonm :an annular seal, a stop on said hammer limiting upward movement of said valve on said hammer, a second annular ledge in said housing below said valve, a collar on said hammer below said second ledge adapted to penetrate said second ledge and -form a sliding seal therewith, a third annular ledge in said housing below said second annular ledge, Aan enlargement on said hammer below said third ledge vadapted to penetrate said third ledge :and form a sliding seal therewith, the longitudinal distance between said third ledge and said enlargement being greater than the longitudinal distance between said second 'ledge and said 8 collar, :a bit stem Vslidably ydisposed in and sealed against said housing below said hammer and having 'a longitudinal central passageway, the upper end of said Ibit stem being disposed to V.be struck by the lower end of said hammer, and a passageway leading from said longitudinal central passage of said hammer to a point outside said hammer proximately below said valve.

References Cited in the jile of this patent UNITED STATES PATENTS 2,580,203 Topanelian Dec. 25, 1951 2,661,928 Topanelian Dec. 8, 195-3 2,851,010 Mori Sept. 9, 19g-58 2,851,251 Sept. 9, 1958 

1. A FLUID-OPERATED WELL-DRILLING MECHANISM COMPRISING A TUBULAR HOUSING, AN INVERTED CUP-LIKE CYLINDER LONGITUDINALLY MOUNTED IN THE TOP OF SAID HOUSING, MEANS AFFORDING OPERATING FLUID ACCESS TO THE INTERIOR OF SAID HOUSING BELOW SAID CYLINDER, AN ELONGATE ANNULAR HAMMER SMALLER IN DIAMETER THAN THE INSIDE DIAMETER OF SAID HOUSING AND SLIDABLY DISPOSED IN AND SEALED AGAINST THE INSIDE OF SAID CYLINDER, SAID HAMMER HAVING A LONGITUDINAL CENTRAL PASSAGE THERETHROUGH, AN ANNULAR VALVE SLIDABLY DISPOSED ON AND SEALED AGAINST THE OUTSIDE SURFACE OF SAID HAMMER, THE INSIDE DIAMETER OF SAID VALVE BEING LESS THAN THE INSIDE DIAMETER OF SAID CYLINDER, A PASSAGEWAY LEADING FROM SAID LONGITUDINAL CENTRAL PASSAGE OF SAID HAMMER TO A POINT OUTSIDE SAID HAMMER PROXIMATELY BELOW SAID VALVE, A FIRST ANNULAR LEDGE ON THE INSIDE SURFACE OF SAID HOUSING BELOW SAID VALVE, THE LOWER END OF SAID VALVE BEING ADAPTED TO SEAT ON THE UPPER PORTION OF SAID FIRST LEDGE TO FORM AN ANNULAR SEAL, A STOP ON SAID HAMMER LIMITING UPWARD MOVEMENT OF SAID VALVE ON SAID HAMMER, A SECOND ANNULAR LEDGE IN SAID HOUSING BELOW SAID VALVE, A COLLAR ON SAID HAMMER BELOW SAID SECOND LEDGE ADAPTED TO PENETRATE SAID SECOND LEDGE AND FORM A SLIDING SEAL THEREWITH, AND A BIT STEM SLIDABLY DISPOSED IN AND SEALED AGAINST SAID HOUSING BELOW SAID HAMMER AND HAVING A LONGITUDINAL CENTRAL PASSAGE, THE UPPER END OF SAID BIT STEM BEING DISPOSED TO BE STRUCK BY THE LOWER END OF SAID HAMMER. 